Electric heating devices are widely used in people's daily lives, especially electric blankets, hot compress pads and so on. However, existing electric heating devices usually heats with power on and stops heating with power off. Therefore, when an electric heating device is used, the user needs to switch off the power manually when the electric heating device reaches a specific temperature. The electric heating device will continually heat up if the power is not switched off manually, eventually resulting in a spontaneous combustion. This is a safety loophole and at the same time, when powered off for a period, the electric heating device needs to be restarted by a user manually, which is very inconvenient and provides a poor user experience.
Therefore, it is very necessary to have a constant-temperature controlled circuit, which can automatically cutoff the power when the electric heating device reaches a predetermined temperature and can also automatically heat up when the temperature of the electric heating device comes down to another predetermined value, to overcome the above disadvantages.